Treesearch

Fuels burned by either prescribed or wildfires are complex and important components of forested ecosystems. Fine fuels consisting of fallen limbs, twigs, and leaves of shrubs and trees are rich in nutrients. If these fuels are not immediately burned, nutrients can leach from these materials into the forest floor, especially if they overwinter. Larger fuels consisting of standing dead trees, large limbs, and down logs or coarse woody debris (CWD) play critical roles in fixing and storing nitrogen (N), protecting the soil surface, and suppling organic matter to the forest floor. Up to 40% of...

Disturbances are natural and essential components of healthy ecosystems, but their ecological roles in the maintenance of endemic conditions for an area (that is, long-established levels of activity that are of low magnitude and relatively static intensity and cause unnoticed or relatively low amounts of tree killing, defoliation, or deformation) are poorly understood. The purpose of this study was to develop a conceptual model of stand development that links stand structure with underlying tree-killing disturbances. Transect surveys were used to identify and assess stand structure of a...

Limber pine (Pinus flexilis James) grows across a wider range of elevations than any other tree species in the central Rockies, from ;1600 m at Pawnee Buttes to .3300 m at Rollins Pass. In this study we investigated two possible explanations for limber pine’s success across a broad range of elevations: (1) the sites on which it is found, although separated by .1000 m elevation, may not be very different with respect to environmental factors that affect tree growth, and (2) limber pine growth is insensitive to environmental factors that change with elevation. We compared site characteristics...

Resource managers lack an inexpensive and quantifiable method to detect lynx presence across large landscapes. We tested efficacy of a protocol based on hair snagging to detect presence of lynx (Lynx canadensis). We tested 2 key elements of the protocol: 1) a hair-snaring device and 2) commercial lures used to attract and elicit rubbing behavior in lynx. The commercial lures we tested included: 1) beaver (Castor canadensis) castoreum and catnip oil, 2) Cat Passion, 3) Pacific Call, 4) Hawbacker's Cat lure #1) and 5) BB1. To compare detection rates among lures, we randomly placed lures at...

Northern Goshawks (Accipiter gentiles) nesting in south central Wyoming consumed at least 33 species of prey; 14 were mammals and 19 were birds. Based on percent occurrence in regurgitated pellets, dominant (>10% frequency) prey species included: red squirrel (Tamiasciurus hudsonicus; present in 50% of pellets), Northern Flicker (Colaptes auratus; 34%), American Robin (Turdus migratorius; 30%), golden-mantled ground squirrel (Spermophilus lateralis; 27%), and Uinta or least chipmunk (Tamias spp.; 10%). Woodpeckers [combined frequency of occurrence for Northern Flicker, Red-naped Sapsucker...

Red Squirrels (Tamiasciurus hudsonicus) routinely breed biannually in eastern North America, but normally breed once annually in western North America. However, a postpartum estrus resulting in two breeding seasons per year has been documented within the maritime region of British Columbia. I present two accounts of Red Squirrel behavior suggestive of autumn breeding in Red Squirrels in western Montana, and supporting evidence from the literature suggesting that late-season breeding resulting from a postpartum estrus may occur periodically in Red Squirrels within the Rocky Mountains.

Release of exotic insects as biological control agents is a common approach to controlling exotic plants. Though controversy has ensued regarding the deleterious direct effects of biological control agents to non-target species, few have examined the indirect effects of a "well-behaved" biological control agent on native fauna. We studied a grassland in west-central Montana infested with spotted knapweed (Centaurea maculosa) to examine the effects of knapweed invasion and two gall fly biological control agents (Urophora affinis and U. quadrifasciata) on the native deer mouse (Peromyscus...

A simple analytical formula is developed for estimating the frequency attenuation of eddy covariance fluxes due to sensor response, path-length averaging, sensor separation, signal processing, and flux averaging periods. Although it is an approximation based on flat terrain cospectra, this analytical formula should have broader applicability than just flat-terrain providing the peak frequencies of the logarithmic cospectra are known. Comparing the integral and analytical formulations for momentum flux, heat flux, vapor flux, and closed-path and open-path CO2 eddy covariance systems...

As a result of anthropogenic combustion processes, ecosystems in the eastern and western United States and Europe have experienced elevated atmospheric deposition of nitrogen for most of this century and have begun to show symptoms of decline. If there is a cause and effect relationship between nitrogen deposition and ecosystem decline, one would expect that the current symptoms are a result of the cumulative effect of years of deposition. Deposition of anthropogenically produced nitrogenous compounds has increased along the Colorado Front Range in the past decades as a result of increased...

Diseases and other small-scale disturbances alter spatial patterns of heterogeneity in forests by killing trees. Canopy gaps caused by tree death are a common feature of forests. Because gaps are caused by different disturbances acting at different times and places, operationally determining the locations of gap edges is often difficult. In this study, digital image analysis using aerial photos was used to formulate an operational definition of gaps and to compare spatial attributes of canopy gap structure in previously unharvested and harvested stands of ponderosa pine forests in the...